sin23π24=2p−q−14rthen the value of p2−q2−r2=

sin23π24=sinπ-π24                   =sinπ24We have 2sin2π24=1-cosπ12                                 =1-cos15°∴sin2π24=1-3+1222⇒sinπ24=22-3-142⇒p=2,q=3 and r=2⇒p2+q2-r2=9